1. Field of the Invention:
The present invention relates to a door window regulator which vertically moves and guides a door window glass of an automobile.
2. Description of the Prior Art:
In general, a door window regulator has an X-shaped arm made from steel sheet and is arranged such that a door window glass mounted on the upper end of the X-shaped arm is vertically moved by the pivoting of the X-shaped arm. The door window regulator employing such an X-shaped arm has a relatively large weight and a relatively large moving locus, which fact disadvantageously limits the range of available configurations and structures of the door.
In view of this fact, door window regulators have heretofore been proposed in which a wire is employed as a window glass driving means mainly from the viewpoint of reducing the weight of the apparatus.
Such conventional door windor regulators include those shown in the specifications of Japanese Patant Publication No. 31,485/1971, U.S. Pat. No. 4,110,935 and B.P. No. 631,130. In these prior arts, pulleys are rotatably supported on the door, and a wire is disposed between these pulleys. This type of door window regulator, however, involves a troublesome operation when disposing the wire within the narrow space between the inner and outer panels of the door and requires an additional operation when mounting a guide for guiding the vertical movement of the window glass on the door, as well as the operation of mounting the pulleys on the door. It may not be necessary to provide any guide for guiding the vertical movement of the window glass on an automobile in which a sash for guiding the window glass is provided on the upper portion of the door. It is, however, necessary for a so-called sash-less door to be equipped with the guide for the purpose of reliably guiding the movement of the door glass. Further, the proposed door window regulators involve difficulty in controlling the tension of the wire stretched between the pulleys, which fact may unfavorably lead to production of some play between the upper or lower end portion of the window glass and the vehicle body and also an increase in the required operating force and reduction in durability of the apparatus.
Another type of conventional door window regulator has been proposed in the specifications of B.P. No. 1,448,795 and U.S. Pat. No. 4,109,417 in which pulleys are rotatably supported on a guide for guiding the vertical movement of the window glass. In this prior art, a wire driving unit has previously been formed as a subassembly in which the wire driving unit is connected to the upper and lower portions of the guide through a wire tube. With such a structure, it is relatively easy to mount the regulator on the door. However, in this structure, a means for preventing any undesired pivotal movement of the window glass in the vertical plane is constituted solely by a combination of the guide and a slider which moves in harness with the guide and, therefore, the rigidity of the regulator required to support the window glass in such a manner that this pivotal movement in the vertical plane is prevented may be insufficient. For this reason, if this structure is applied to a sash-less door, the seal between the upper and side end edges of the window glass and the vehicle body may be incomplete, which fact involves a strong risk of leakage of water or generation of noise as a result of draft entering through a narrow gap. Further, in recent automobiles, the area of the window glass is enlarged for the purpose of increasing the field of view, and the vertical dimension of the slider which is guided by the guide is reduced correspondingly, which fact also unfavorably leads to the window glass being incompletely guided. It is to be noted that this type of door window regulator is formed with a substantially triangular shape as a whole owing to the above-described structure in which the guide and the wire driving unit are connected together as a subassembly. Therefore, when the door window regulator is mounted in the door, it is not possible for the regulator to be inserted into the door in a folded state.
Still another type of conventional door window regulator has been disclosed in the specification of U.S. Pat. No. 3,890,743 in which a pair of guides are connected together by a wire tube, and driving force derived from a driving means is applied to an the intermediate portion of the wire tube. With this structure, accordingly, the door window regulator is formed as a subassembly structure, which permits the assemblability to be improved, and it becomes possible to limit the pivotal movement of the window glass within the vertical plane of the surface of the glass. In this structure, however, since the guides are connected by a bent wire, the wire is easily straightened when an excessively large tension acts on the wire, and if the wire becomes straight, the resistance against the pivotal movement of the glass is unfavorably decreased. Further, since the wire between the guides is bent such as to project both upwardly and downwardly, the height of the door window regulator as a whole is increased, which fact disadvantageously limits the size of the window glass. Furthermore, since the wire is passed through a bent wire tube, frictional resistance occurring therebetween causes an increase in the operating force required when raising or lowering the window glass.